When people are engaged in underwater work/scientific research/recreation and entertainment (sports), it is frequent to use various underwater tools and particularly an electronic product and it is inevitable to use a button switch in operation control. In order to prevent the button switch after contacting water from shorting out or causing other failures, an isolation hood is often provided for the button switch, so that not only may the button switch be operated, but the effective water resistance may also be achieved.
For a common underwater normally-open button switch, the switch which needs to be controlled by a button is arranged in a sealed housing, the button is mounted on the top of the sealed housing, a shaft of the button is penetrated through the top surface of the sealed housing and rightly faces to the switch, a sealing ring is arranged at the junction of the button and the sealed housing, and the button is rebounded via a spring.
Since there is a huge pressure difference between the inside and the outside of the sealed housing in underwater (for example, the pressure difference in 40 m underwater is 4 kg/cm2) and the pressure difference varies along with the change of the diving depth, the conventional art/product structure has the following problems and defects.
In order to resist the huge pressure in underwater and not to damage the switch and a controlled underwater article thereof after water enters, the sealing ring and the shaft of the button must be in a tight fit. However, such a manner will generate a huge impedance effect to the activity of the button so that pressing of the button is labor-consuming, the resilience is inaccurate and at last the operation is wrong.
In underwater, the pressure difference between the inside and the outside of the sealed housing is very large, so it is required that the spring must have enough elasticity to resist the pressure difference. However, an excessively hard spring also easily results in that the operation of the button is inconvenient.
In light of the above two points, when the switch is pressed at a shallow water depth, it is labor-consuming to press the button. At a deep water depth, the switch cannot be reset due to the huge underwater pressure, a user completely has no feeling to trigger the switch, many false actions are caused and the task is failed.
Due to the fact that the button is frequently pressed/reset, the sealing ring and the button shaft leak easily under the huge pressure difference, the safety and the reliability are poor and the frequent maintenance and replacement bring inconvenience to the user.
Moreover, with the high requirement on the material and machining precision of the button shaft and the sealing ring, the high cost, the high manufacturing and maintenance cost and the frequent maintenance, the experience of the user is affected. Therefore, the convention art still has some defects.